Stewart- d



(No Model.

S. D. MOKBLVBY. MAGNETO TELEPHONE.

Patented Apr. 3, 1894.

1 4, abhor/wen IIIIIIIIIIIII HOGRAP'HING cOMPANY.

UNITED STATES PATENT OFFICE.

' STEWART. n'mexE vnv, OF CANTON, OHIO, ASSIGNOR OF ONE-THIRD To JOSEPHA. LINVILLE, OF SAME PLACE.

MA GNETO-TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 517,763, dated. April3,1894. Application filed September 13,1893. Serial No. 485,430. (Nomodel.)

To all whom it may concern.-

Be it known that I, STEWART D. MOKELVEY, a citizen of the United States,residing at Canton, in the county of Stark and State of Ohio, haveinvented new and useful Improvements in Receivers for ElectricTelephones, Speaking-Telegraphs, Phonautographic Apparatus, and otherPurposes, of which the following is a specification.

My invention relatesto receivers for electric telephones, speakingtelegraphs, phonautographic apparatus, and-other purposes.

It is the object of my invention to provide a receiver which shall beofsimple and economical construction, and to combine therewith. a bi-polarpermanent magnet, having upon each of its opposite poles a steel coreupon which is mounted a bobbin of fine wire connected in the secondarycircuit, while the other bobbin is connected up in a tertiary circuit,whereby I am able to reproduce sounds of widely varying'intensity andincrease the distinctness of all impulses transmitted. 7

It is my purpose, also, to provide a telephone rcceiver having anincreased area of 1 vibratory diaphragm, so arranged in connection withan inclosed air-chamber as to set up a series of largely amplifiedvibrations which are concentrated upon the tympanum with largelyreinforced effect. 7

It is'my further purpose to provide simple means whereby the receivingdiaphragms shall have elastic support upon the wall of a circularair-chamber which has communication with the exit-opening of thereceiver, whereby the pulsations set up in said chamber are reinforcedupon opposite sides of the same, the phases of audible speech reproducedwith increased accuracy and the in tensity of the sound wavesmultiplied.

My invention consists in the novel features of construction, and in theparts and new combination of parts hereinafter fully described and thenparticularly pointed out and defined in the claims.

To enable those skilled in the art to which my said invention pertainsto understand and to make, construct or use the same, I will describethe invention in detail, reference being had to the accompanyingdrawings,in which- Figure 1 is aperspective view of a telephone receiverconstructed in accordance with my invention. Fig. 2 is a centrallongitudinal section of the parts shown in Fig. 1. Fig. 3

is a similar section, the receiverbeing turned one fourth around, ascompared with its position in Fig. 2. Fig. 4 is aview of one of thediaphragms of the receiver. Fig. 5 is a perspective view of'the cleftelastic ring which forms the wall of the air chamber. Fig. 6 is a. view'of the second diaphragm, the parts shown in Figs. 4, 5 and 6 beingseparated, but shownin their proper position relatively to each other.Fig. 7 is a perspective viewof the polar extremities of the permanentmagnet, showing the bobbins mounted upon their cores.

In the said drawings the reference numeral 1 indicates the shell, orcasing of the receiver, provided with a handle 2, of any suitable form.The shell and handle are formed usually of hard rubber, though othersuitable material may be employed. The shell is formed in two equal orsimilar parts in which is formed a chamber 3 communicating with acentral channel, or exit-opening 4. In the ameter, its outer,cylindrical surface being threaded to enter a counterbored opening inthe handle 2. The other end of the shell is provided with a screw cap 7having a central orifice 8, which registers with the exit-opening 4.This screw-cap, in conjunction with the handle, holds the two partscomposing the shell closely and firmly together. The interior of thehandle is bored out to form a chamber 9, to contain part of thepermanent magnet. The permanent magnet is formed of steel, the bar beingbent at its middle point to bring the two legs 10 of said magnet intoclose proximity. .These legs have a slight divergence normally, andtheir extremities are bent outwardly, or away fromeach other, as shownin Figs. 3 and 7, and are then turned, into parallelism, or proximatelyso, forming polar extremities 12. Upon each of the latter is mounted asteel core 13, its end being seated in a vrecess in the inner face ofthe end 12, of the permanent magnet, and a'screw 14,

is passed through the latter and tapped into the core. Upon each core ismounted a bobbin, consisting of heads, or ends15, of insulatingmaterial, which are slipped upon the core, one resting against the innerface of the end 12 of the permanent magnet and the other being upon theunsupported extremity of the core 13. The bobbin is wound with fine wire16, the terminals of which are brought out through apertures in. theother head 15, and connected in the manner hereinafter explained.

The construction of the parts described is such that when the cores arein place and the bobbins mounted thereon, there will be a space betweenthe free, or unsupported ends .of said cores equal to, or somewhatgreater than, the diameter of the exit-opening 4. In this interveningspace is arranged an elastic ring, or rubber annulus 17, provided withan opening 18, which is formed by cutting away a small portion of saidannulus. This opening is so placed as to be directly above the steelcores l3, and in avertical plane passing through their axis, as shown bydotted lines in Fig. 2. The rubber annulus 17 is of greater diameter,internally, than the diameter of the heads 15 of the bobbins, andbetween thelatter and said annulus are placed diaphragms 19, having suchdiameters that their peripheries are flush, or substantially so, withthe exterior of the rubber annulus. By this arrangement and by theconstruction of the threaded ends of the two-part shell 1, the twodiaphragms 19 are pressed by the parts of said shell closely against theannulus 17, thereby forming an air-chamber which is wholly inclosed saveonly the narrow exitopening 18. The cores 13 are thus so placed thattheir ends lie close to, but not in contact with, the outer faces of thediaphragms 19, and their position, relatively to said diaphragms, isadjusted by means of a loop 20, which is slipped over the legs of thepermament magnet as shown in Fig. 3.

The permanent magnet with its attached parts is arranged within theshell 1 andbody 2 as shown in Figs. 2 and 3, the exit-opening 18 in thecircular wall of the air-chamber inclosed by the rubber annulus 17,being located immediately beneath and in line with the exit-opening atand the orifice 8 in the screw cap. The terminals 21 of the fine wire16, upon one of the bobbins, are connected with the secondary circuitand the terminals 22 of the other bobbin are, in a similar manner,connected with a tertiary, or third circuit. Any ordinary four-conductorcord 23 may be used for this purpose, and I have found it convenient tocarry such a cord through the opening in the end of the handle 2, asshown in Fig. 3, and loop itaround the neutral portion of the permanentmagnet, in order to prevent it from pulling out. It should be noted,however, that I may, without any change of construction, use one side,only, and in this event atwo conductor cord may be used.

In the construction of the ting or annulus 17, I prefer to use a rubbercompound, having a degree of vulcanization which willpermit aconsiderable elasticity to remain in the ring, but I may use any othercompound, or any material suitable for the purpose.

When the receiver is used with the Bell telephone, the fine wires 16 ofthe bobbins may be connected in series, a terminal of one beingconnected with the secondary of the induction coil and a terminal of theother with the main line. A like connection may be made upon one side ofthe permanent magnet, only, if this is desired. When made upon bothsidesit is evident that the two diaphragms will act in unison and willrespond equally to the same electric pulsations.

What I claim is- 1. A receiver for telegraphic, telephonic,phonautographic and other apparatus, having a shell formed in two equaland similar parts which are united by a screw-cap and a handle engagingwith the ends of said shell, substantially as described.

2. A receiver for the uses set forth, having a shell formed in two partswhich when united inclose a chamber adapted to receive the polarextremities of a permanent magnet, a screwcap turned upon one end ofsaid shell and a handle having a threaded, counter-bored recess toreceive a threaded neck on the other end of said shell, substantially asdescribed.

3. The combination with a permanent magnet having bi-po1ar extremitiesbrought opposite each other, of steel cores mounted upon the inner, oradjacent faces of said extremi suitable chamber provided with anexit-opem ing and a screw-cap having an orifice, of a permanent magnethaving steel cores upon its two polar extremities, bobbins mounted 011said cores, the terminals of one connected up with a secondary and theterminals of the other with a tertiary circuit, an elastic ringinterposed between the ends of the steel cores and having a portionremoved beneath the exit-opening of the shell, and diaphragms insertedbetween the ring and said cores, substantially as described.

5. The combination with apermanent magnet composed of a bar which isbent at its middle portion to form a two-part, divergent shank and bringits polar extremities opposite each other, of steel cores projectingfrom said extremities,bobbins mounted on said cores, an elastic ringinterposed between the inner ends of said cores and having an opening,diaphragms inserted between the ring and cores, and a loop movable uponthe two" part shank of the magnet, substantially as described.

6. The combination witha permanent magnot having bi-polar extremitiesbrought opposite each other, of cores mounted upon the adjacent faces ofsaid extremities, an elastic ring arranged between said cores andprovided with an opening, diaphragms interposed between the oppositesides of said ring and the ends of said cores, and a two-part shell orcasing, having an exit-opening and an orifice in its cap, arrangeddirectly over and in line with the opening in the ring, the parts ofsaid casing having bearing against the peripheries of the saiddiaphragms located therein to clamp said diaphragms against the elasticring, substantially as described.

7. The combination with a permanent magnet having bi-polarextremitieswhich are nesses, I I

STEWART D. MOKELVEY. Witnesses:

JAMES L. NORRIS, THOS. A. GREEN.

